The treatment of locally advanced cancer of the cervix with radiation has been significantly improved with the introduction of perineum templates for the application of both intracavitary and interstitial transperineal and parametrial implants. Conventional templates that have been developed for this purpose are the Syed-Neblett and MUPIT templates. A full description of these prior art templates may be found in Martinez, A., Cox, R. S., and G. K. Edmundson, "A Multiple-Site Perineal Applicator (MUPIT) for Treatment of Prostatic, Anorectal and Gynecologic Malignancies," Int. J. Radiat Oncol., Biol., Phys. 10:297-305 (1985); and Syed, A.M.N., Puthawala, W., Neblett, D.L., et al., "Transperineal Interstitial-Intracavitary `Syed-Neblett` Applicator in the Treatment of Carcinoma in the Uterine Cervix," Endocuire Hyperther. Oncol. 2:1-13 (1987).
Problems have been encountered in using the commercially available Syed-Neblett templates. First, it is often impossible to insert the needles through the peripheral rows of this template because of anatomic limitations, in particular pelvic bone interposition. In this case, the lateral parametria and pelvic sidewalls do not receive an adequate radiation dose. Second, there has been seen significant crowding and "coning down" of the needles at the cephalad ends because of interference with the ischial tuberosities and associated ligaments. This leads to significant dose inhomogeneities, especially when a central tandem is also used. Finally, the one-centimeter spacing between needles within the treatment volume results in a large number of needles that must be correctly identified on the films for dosimetry.
The MUPIT device is an attempt to provide an all-purpose template for the interstitial radiotherapy of cervical, rectal, prostate and female urethral cancer. The MUPIT template is relatively large and is provided mostly with needle holes that are parallel to the obturator. It thus has the same coning-down and pelvic bone interposition problems as the Syed-Neblett template. In the MUPIT template, the outer rows of needle holes are angled; however, the holes for the outer needles are four centimeters lateral to the center of the template. Often, the anatomy does not allow the insertion of the needles as far laterally as both designs demand. A need has therefore arisen for a novel gynecological template that will cure the problems inherent in the Syed-Neblett and MUPIT designs.